The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems may be used to etch or deposit layers on substrates such as semiconductor wafers. In some examples, an exposed surface of the substrate may include a top surface and one or more trenches including side walls and a trench bottom. In some applications, it may be desirable to deposit a film with a uniform thickness on two or more of the top surface, the side walls and/or the trench bottom.
Superconformality is defined as the ratio of conformal film deposition (CFD) oxide thickness on a trench sidewall (vertical feature) relative to a trench bottom or top surface (horizontal feature). Different applications may require different step coverage of CFD oxide.
For example, CFD oxide films that may be used as through-silicon via (TSV) liners may need to have a predetermined thickness on the sidewalls to meet dielectric requirements. In this application, the CFD oxide film is preferably superconformal. A higher deposition rate for the sidewall features impacts throughput favorably. Furthermore, a thinner film on the top horizontal surface allows faster and lower cost chemical mechanical polishing (CMP). In other words, step coverage greater than 100% may be desirable in this application.
Alternatively, for other CFD oxide films, such as dielectric spacers, 100% step coverage may be important.